Bioengineering Laboratory, Department of Orthopaedic Surgery, Louisiana State University, New Orleans, Louisiana, USA.
J Electromyogr Kinesiol. 1993;3(1):33-40. doi: 10.1016/1050-6411(93)90021-N.
The purpose of this study was to determine if differences exist between the control strategies of the elbow flexor and extensor muscles performing stepwise and linearly increasing isometric contractions, and to determine their control strategy when active as antagonists to each other. The electromyogram (EMG) from the biceps brachii and triceps brachii were recorded during stepwise and linearly increasing contractions in flexion and extension. The power density spectrum of the EMG was determined and the median frequency (MF) for each spectrum was calculated for assessment of changes in the average conduction velocity, which reflects motor unit recruitment and derecruitment, and thereby the control strategy of the muscle. The results suggest that differences exist in the control strategies employed by a single muscle during stepwise and linearly increasing contractions. Furthermore, the antagonist triceps recruits motor units up to a higher force level during stepwise contractions than during linearly increasing contractions. The antagonist biceps derecruits motor units up to a higher force level during linearly increasing contractions than during stepwise contractions.
本研究旨在确定在进行逐步和线性递增等长收缩时，屈肌和伸肌的控制策略是否存在差异，并确定它们在作为拮抗剂相互作用时的控制策略。在屈伸过程中，记录肱二头肌和肱三头肌的肌电图（EMG）。确定 EMG 的功率谱密度，并计算每个谱的中值频率（MF），以评估平均传导速度的变化，这反映了运动单位的募集和去募集，从而反映肌肉的控制策略。结果表明，在进行逐步和线性递增收缩时，单一肌肉采用的控制策略存在差异。此外，在逐步收缩过程中，拮抗肌肱三头肌募集的运动单位达到更高的力水平，而在线性递增收缩过程中则募集的运动单位较少。在线性递增收缩过程中，拮抗肌肱二头肌去募集的运动单位达到更高的力水平，而在逐步收缩过程中则去募集的运动单位较少。
